Upgrading gasoline

ABSTRACT

AN OLEFINIC GASOLINE IS CONVERTED TO PRODUCE HIGHER OCTANE PRODUCTS BY ALKYLATING THE C5 FRACTION, EXTRACTING THE C7 FRACTION TO REMOVE AROMATICS, DEHYDROCYCLIZING THE RAFFINATE TO PRODUCE ADDITIONAL AROMATICS AND CYCLING AT LEAST ONE MATERIAL IN THE C3 TO C5 RANGE FROM THE DEHYDROCYCLIZATION PRODUCT TO THE ALKYLATION STEP.

Aprilia, 1974 L. E. DREHMAN ET AL UPGRADING GASOLINE Filednec. 2v,V 1972 2 Sheets-Sheet 1 April 16, 1974 L. E. DREHMAN ET AL UPGRADINGGASOLINE 2 Sheets-Sheet 2 Filed Dec. 2?, 1972 United States Patent ice 3,804,745 UPGRADING GASOLINE Lewis E. Drehman and Floyd Farha, Jr., Bartlesville, Okla., assignors to Phillips Petroleum CompanyA Filed Dec. 27, 1972, Ser. No. 318,706 Int. Cl. Cg 39/00 U.S. Cl. 208-80 4 3 Claims ABSTRACT 0F THE DISCLOSURE An olenic gasoline is converted to produce higher octane products by alkylating the C5 fraction, extracting the C, fraction to remove aromatics, dehydrocyclizing the rainate to produce additional aromatics and cycling at least one material in the C3 to C5 range from the dehydrocyclization product to the alkylation step.

In order to reduce undesirable emissions from internal combustion engines used in automobiles to a minimum in some instances it is desirable to utilize catalytic converters associated with the exhaust system to treat the exhaust gases prior to venting to the atmosphere. When using such `a catalyst it is often desirable to remove completely or to reduce the amount of tetraethyl lead used in the gasoline. Therefore, in such instances, it becomes important to produce gasolines having as high an octane number as possible without lead addition. The present invention is directed toward upgrading olefin-containing gasoline by conversions to produce higher octane components.

According to the invention a gasoline feed is upgraded by separating it to produce a C5 stream, a C5 stream and a C7 stream, alkylating the C5 stream with isobutane, dehydrogenating the remaining pentanes, feeding a dehydrogenated product to the alkylation step, solvent extracting the C7 stream to recover aromatics, dehydrocyclizing the raffinate stream to produce additional aromatics and feeding at least one component of the dehydrocyclization in the range of C3 to C5 to the alkylation step.

In the drawing, FIG. 1 and FIG. 2 are diagrammatic flow sheets of two embodiments of the invention.

In the embodiment of FIG. 1 an olen-containing gasoline stream is fed through pipe 11 to separation zone 12. A C5 fraction is removed through pipe 13, a C5 fraction through pipe 14V and a C7 fraction through pipe 16. The C5 fraction is fed to alkylation zone 17 along with isobutane from pipe 18. The alkylated product is passed through pipe 19 to separation zone 21. The alkylate is removed through pipe 22, isobutane is recycled through pipe 23 and pipe 24 to alkylation zone 17. `Propane and butanes are removed through pipe 25. The C5 fraction isv fed through pipe 26 to dehydrogenation zone 27. The product of the dehydrogenation step is fed through pipe 28 to separation zone 29.

The C, fraction from pipe 16 is solvent extracted in solvent extraction zone 31 and the aromatic extract fraction is recovered through pipe 42. The rainate is fed through pipe 33 to dehydrocyclization zone 34 and the product, containing additional aromatics, is fed through pipe 36 to separation zone 37. A fraction comprising benzene, toluene and C7+ is passed through pipe 38 and returned to solvent extraction zone 31 while the remaining lighter fractions are passed through pipe 39 to separation zone 29. From separation zone 29 a light fraction comprising hydrogen, carbon dioxide and C1-C2 hydrocarbons is removed through pipe 41. A C3-C5 fraction is returned through pipe 42 and pipe 24 to alkylation zone 17 while the C5 fraction is removed through pipe 43 and can be combined with the C5 fraction in pipe 14.

In FIG. 2 a gasoline fraction is fed through pipe 44 to separation zone 46. A fraction comprising C5 hy- 3,804,745 Patented Apr. 16, 1974 pipe S8, propane and butanes removed through pipe 59,

isobutane recycled through pipe 60, and C5s passed to dehydrogenation zone 61 through pipe 62. The product of the dehydrogenation step is fed through pipe 63 to separation zone 64.

The C, fraction from pipe 49 is solvent extracted in solvent extraction zone 66 and the aromatic fraction is recovered through pipe 67. The ranate is fed through pipe 68 to dehydrocyclization zone 69 and the product, con-l taining additional aromatics, is fed through pipe 71 to separation zone 64. From separation zone 64 a light fraction comprising any hydrogen, carbon dioxide and C1 and C2 hydrocarbons is removed through pipe 72. The remainder of the products from separation zone 64 are recycled through pipe 73 to separation zone 46.

The aromatic extraction zone of the process of the present invention can comprise any conventional method for separating aromatics from other hydrocarbons. One example is a solvent extraction unit (Undex Unit) which use, as a solvent, an alkylene glycol, preferably diethylene glycol or a diethylene glycol-triethylene glycol-water mixture. Such a sovent extraction unit can comprise a multistage counter current extraction column associated with appropriate stripper columns, recirculation means, decantation means, washing means, and the like. A highly aromatic stream is discharged from this zone as well as a stream containing C7+ olefins and parans. a

In the pentane dehydrogenation zone, the pentanes are contacted under reaction conditions with any suitable catalyst which has activity for dehydrogenation of paraffins to form monooleins. A number of such catalysts is known. One suitable class of such dehydrogenation catalysts comprises a steam-stable Group II metal aluminate impregnated with a Group VIII metal and a tin-group metal. Particularly preferred are compositions containing zinc aluminate, tin, and platinum. A particularly elfective catalyst is a zinc aluminate (containing a slight excess of zinc) which has been impregnated with 0.4-0.6 weight percent platinum, and 0.4-1 weight percent tin.

The pentane dehydrogenation catalysts operate at 750- 1250 F., preferably 1000-1100 F.; at 0-500 p.s.i.g., pret'- erably 50-300 p.s.i.g.; at a steamzhydrocarbon mole ratio of `0.5-30, preferably 3-20; and at a hydrocarbon space rate of 0.1-10, preferably 0.5-5 LHSV.

In the catalytic dehydrocyclization zone of the process, the C7+ hydrocarbons are contacted, under reaction conditions, with any suitable catalyst which has substantial dehydrocyclization (aromatization) activity. For example, a suitable catalyst is a platinum-containing catalyst prepared by depositing platinum on a cracking catalyst such as silica-alumina. Another suitable catalyst is alumina containing combined halogen such as uorine. Other catalysts which may be utilized in this zone include Group -VIII metals deposited on other supports such as alumina, magnesia, thoria, zirconia, and the like. However, the particularly preferred dehydrocyclization catalyst is the dehydrogenation catalyst comprising a Group VIII metal-promoted Group II metal aluminate described above for use in the pentane dehydrogenation zone. That catalyst, when contacted with Cq+ hydrocarbons, produces substantial amounts of aromatic products with high selectivity. The conditions for the dehydrocyclization zone are essentially identical with the conditions described above for the -pentane dehydrogenation zone.

The alkylation zone can employ any suitable alkylation catalyst using any known alkylation conditions to provide a high octane alkylate. A suitable catalyst is hydrofluoric acid at a temperature of 50-l00 F., a contact time of 1-10 minutes, and a suitably high isobutane ratio (for ex- 4 What is claimed is: 1. A process for upgrading a gasoline feed comprising the steps of:

separating said gasoline feed to produce a rst separated stream comprising a major portion of the C5 content 5 amle, 6-15 moles isobutane per mole of olefin). of said gasoline feed, a second separated stream com- Other than the aromatic extraction zone previously deprising a major portion of the C6 content of said gasoscribed, the separation zones in the process of the invenline feed, and a third separated stream comprising a tion can comprise any suitable means, such as fractional major portion of the C7 content of said gasoline feed; distillation, to achieve the separations indicated. The sep- 10 alkylating said first separated stream with isobutane; aration of the hydrocarbon mixtures shown is within the separating the product stream from said alkylating step skill of the art. to produce an alkylated product stream and a fourth In a calculated example, according to the invention as separated stream comprising pentanes; illustrated in FIG. 2, a catalytic cracked gasoline is fed dehydrogenating said fourth separated stream to prothrough pipe 44. A pentenes and lighter fraction is fed duce a dehydrogenation product stream; through pipe 47, a stream comprising a 1Z0-185 F. boilfeeding at least one component of said dehydrogenation ing fraction through pipe 48 and a 18S-3 00 F. boiling product stream in the range of C3 to C5 to said alkylatfraction through pipe 49. 'Ihe 300 boiling plus fraction is step; taken through pipe 51. solvent extracting said third separated stream to pro- Alkylation zone S2 is an HF alkylation zone operated 20 duce an extract stream containing aromatic comat a temperature of about F., suicient pressure to pounds and a raffinate stream; maintain liquid phase with a HF/hydrocarbon volume dehydrocyclizing said rafnate stream to produce a deratio of 4:1, an isobutane/olefin mole ratio of 12:1 and hydrocyclization product stream; with an average contact time of about 1 minute. Solvent feeding at least one component of said dehydrocyclizaextraction zone 66 is a diethylene glycol extraction step 25 tion stream inthe range of C3 to C5 to said alkylation operated at a temperature of about F., a pressure of step; and p.s.i.g. and with a solvent/hydrocarbon liquid liquid recycling a C, component of said dehydrocyclization volume ratio of about 4:1. Dehydrogenation zone 61 stream to said dehydrocyclization step. presents a dehydrogenat'ion step utilizing a platinum/ tin/ 2. A process according to claim 1 wherein said gasoline zinc aluminate catalyst at a temperature of 1050 F., a 30 feed is separated ina rst separation zone; pressure of 100 p.s.i.g., a ratio of moles of steam to moles said product stream from said alkylating step is sepof hydrocarbon of about 7 and with a gaseous weight hourarated in a second separation zone; ly space velocity of about 1000. Dehydrocyclization zone isobutane is recycled from said second separation zone 69 represents a step utilizing a platiuum/tin/zinc aluminate 35 to said alkylation zone; catalyst at about 1050 F., 100 p.s.i.g. a ratio of moles said dehydrogenation product stream is separated in a of steam to moles of hydrocarbon of about 7 and a liquid third separation zone; hourly space velocity of about 1.5. said dehydrocyclization product stream is separated in The results are shown in the following table. The irna fourth separation zone; provement in octane number is clearly demonstrated. 40 a stream comprising benzene, toluene and C7+ hydro- TABLE stream number 44 47 4s 49 51 54 50 5s Boiling range, F 50-450 120 12o-185 1e5-300 300+ 12o-400 Composition, bbl./100 bbl. feed:

Hz-Czs l Propane- 0. 41 Propylene. 0. 78 Butene. 0. 24 0. 67 Tenhnfnnn 13. 75 Butylenes- 0. 84 1. 73 Pentanes- 0.09 7. 34 10.07 Pentenes 4. 03 7. 87 x20-135 F b 17.33 17.92 18s-300 F b 30. s0 01. 72 300 F. 30.10 30.10 Aromatics (BTX plus 00)' 9. 87 2. 73 24. 56 Alkywe 10.59 10.59

Total bbl 100.02 18.30 20.05 30.28 30.10 13.75 2s. 05 10.59

Research octane number plus 0 88. 2 97. 0 84. 6 93. 0

Btream number 60 62 63 67 68 71 72 73 Bolling range, F 185-300 Congestion, b1/100 bbl. feed:

2-01'0 201. o Propane- 0. 72 41 Propylene 78 Butane. 0. 67 43 Ten'hnfnnn Butylenes. .89 Pentanes. 10. 67 6. 65 Pentenes.- 3.84

i000 BTX 1 c 30.88

6 ronmcs( pus 0) 17.42

Total bbl 1.39 10.07 51.08

Research octane number plus 0. 112

l MSCF; b Aromatic free. Benzene, toluene, xylene plus 0|.

carbons is returned from said fourth separation zone to said solvent extraction zone;

a stream comprising Vthe remaining lighter fractions is passed from said fourth separation zone to said third separation zone; and

a C3-C5 fraction is returned from said third separation zone to said alkylation zone.

3. A process according to claim 1 wherein:

said gasoline feed is separated in a first separation zone;

the product stream from said alkylation step is separated in a second separation zone;

separate streams one comprising propane and butanes and the other comprising alkylate are removed from said second separation zone;

sobutane is recycled from said second separation zone 15 to said alkylation zone;

said dehydrogenation product stream and said dehydrogenation product stream are both fed to a third separation zone; and

said at least one component of saiddehydrocyclization stream in the range of C3 to C5 is fed to said alkylation step by passage from said third separation zone to said rst separation zone.

References Cited UNITED STATES PATENTS 2,890,997 6/ 1959 Hrschler 208-93 3,003,049 10/ 1961 Hamilton 208-93 3,409,540 11/ 1968 Gould et al 208-93 3,410,788 11/ 1968 Drehman 208-87 3,657,109 4/ 1972 Beyaert 208-80 HERBERT LEVINE, Primary Examiner U.S. Cl. X.R.

UNITED PATENT FFIGE csn'rrrcxr or comcTloN v Dated: April 16, 197i,

Lewis E. Drehmanand Floyd Farha, Jr.

Y It is certified that error appears in the above-identified patent and that. said Letters Patent arehereby corrected as shown below:

ciumnzulme 17, delen ffalkylat-- and 'insert --Qalkylung clumn 5, une

Patent No., 3,801,715

Siged` ,and 'sealed this lst day of October 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. Y C. r/nxRsHALL DANN Attesting Officer Commissioner of Patents 

